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Pharmacology -- Test #2 > Antiviral Drugs I > Flashcards

Antiviral Drugs I Flashcards

1
Q

Why are there so few antivirals?

A

Most things that will kill a virus kill host cells

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2
Q

Two ways to interfere with virus specific function

A

Interfere with function unique to virus

Host function is much less susceptible

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3
Q

Viral specific enzyme examples?

A 
Proteases
mRNA capping enzyme
Neuraminidase
Ribonucleases
Kinases
Integrases
Uncoating Enzymes
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4
Q

Effective antivirals have a therapeutic index of…

A

100 to 1000

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5
Q

T or F. Antiviral resistance is rare.

A

False

Becoming more and more common

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6
Q

Chronic viral infections are caused by…

A

ability of the virus to become latent

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7
Q

Stages of viral replication targeted for therapy

A 
Prevention of entry into host cells
Inhibition of uncoating
Integrase Inhibitors
Duplication of genome
Transcription
Translation and Post-Translational modification
Assembly
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8
Q

Three envisioned subclasses of drugs that prevent viral entry into cells

A
  1. Inhibitors that compete to attach at viral receptor
  2. Coreceptor Agonists
  3. Fusion Inhibitors that prevent fusion
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9
Q

Why haven’t drugs that prevent viral entry into host cells ebcome a common thing?

A

Unstable peptides that mimic the receptor

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10
Q

Name the coreceptor antagonist drug in the works for AIDS treatment

A

Maraviroc

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11
Q

How can HIV-1 resist Maraviroc?

A

Using the drug bound CCR5 as a coreceptor

Noncompetitive Resistance

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12
Q

Is Maraviroc intended for treatment naive or treatment experienced patients?

A

Effective for both

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13
Q

Maraviroc dosing should be adjusted if…

A

used with drugs that inhibit or stimulate CYPA3

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14
Q

What is Enfuvirtide?

A

A fusion inhibitor for combination therapy in individuals not responding to current HIV regimens.
Derived from gp41 sequenc

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15
Q

Downside of enfuvirtide?

A

Low oral bioavailability

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16
Q

Virus uncoating corresponds to…

A

Loss of viral protein coat

Fusion of viral lipid membranes

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17
Q

Trigger for viral uncoating?

A

Low pH at the level of the endosomes or lysosomes

fusion with the plasma membrane doesn’t require a pH change

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18
Q

Important viral uncoating drugs

A

Amantidine, Rimantidine

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19
Q

What do you call a drug developed to prevent the insertion of the viral genetic code?

A

INSTIs - Integrase Strand Transfer Inhibitors

Used in AIDS treatment

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20
Q

First approved integrase inhibitor?

A

Raltegravir

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21
Q

Example of a second generation integrase inhibitor?

Why is it better?

A

Dolutegravir

Limited Cross Resistance Profile

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22
Q

Antiviral drugs that act on polymerases are usually…

A

Nucleoside analogs containing altered sugars/bases

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23
Q 
Which class of antivirals is the best?
Why?
A

Drugs that inhibit viral genome duplication

  1. Drug may be activated by virus specific enzymes
  2. Viral polymerases are much more sensitive than host enzymes
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24
Q

One enzyme commonly used to activate antiviral medications with DNA synthesis is…

A

Thymidine Kinase

ex. herpes simplex

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25
Q

Why would a virus need to bring its own kinase (like thymidine kinase)?

A

To allow replication in non-replicating cells (like herpes in neurons)

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26
Q

Why aren’t thymidine kinase drugs active against healthy cells?

A

Thymidine kinase is has much less specificity for what nucleotides it will accept

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27
Q

How do drugs use thymidine kinase to attack virus infected cells?

A

Nucleoside analog admitted
Phos. by thymidine kinase into triphosphate compound
Incorporated into growing nucleic acid chain
Irreversible association with viral polymerase
Termination

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28
Q

Important examples of drugs that inhibit duplication of the viral genome?

A

idoxuridine
Ribaviron
Acyclovir
Gancyclovir

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29
Q

Ways that drugs may target mRNA transcription and processing?

A

Target polyadenylation, methylation, capping, and splicing of Viral RNA

30
Q

Important antivirals that inhiit mRNA transcription and processing.

A

Ribaviron
Interferon
Ribozymes (ex. RNA molecules that induce specific clevage of Nucleic Acids)

31
Q

Specific inhibitors of viral protein translation

A

They are a myth.
The don’t exist.
Let it go.

32
Q

Nonspecific inhibitors of viral protein translation

A

Interferon

33
Q

Post-translational modifications of proteins targeted by anti-virals

A

Glycosylation (fingers crossed)
Phosphorylation (no good drugs yet…)
Fatty acetylation (in the works…)
*Sialidation (Sialidase = Neurominidase)

34
Q

Significance of neuraminidase?

A

Spreads flu from cell to cell by removing sialic acid from the surface, allowing viral particles out

35
Q

Potent inhibitor of viral neuraminidase for Influenza A and B

A

Zanamivir

36
Q

Suspected mechanism for Nitazoxanide

A

Might block glycosylation of hemagluttinin in the golgi
Prevents the molecule from getting to the surface
Can’t get into viral particle

37
Q

Drugs that inhibit assembly of molecular components into the whole virus

A

Ex. Protease Inhibitors in HIV (aquinavir, ritonavir, indinavir)

38
Q

Amantadine is used to treat…

A

Influenza A (not B)

39
Q

Amantadine works by…

A
  1. inhibiting the uncoating of the viral RNA of Influenza A

2. Influences maturation of HA glycoprotein

40
Q

Amantadine is lysosomotropic. So what?

A

This allows it to act on the maturation stage of the virus in the trans-golgi network. It can inhibit acidification.

41
Q

Absorption and elimination of Amantadine?

A

Well absorbed orally

Eliminated unchanged in urine

42
Q

Uses of Amantadine?

A

Oral prophylaxis against Inf. A

43
Q

Side effects of Amantadine?

A

GI Intolerance and CNS complaints

44
Q

Who has greater activity, Amantadine or Rimantidine

A

Rimantidine

45
Q

First generaltion polymerase inhibitor

and actually first antiviral drug

A

Idoxuridine

46
Q

How does idoxuridine work?

A

It is a pyrimidine analog that inhibits viral DNA synthesis after activation by phosphorylation by thymidine kinase

47
Q

Idoxuridine is primarily active against…

A

Used for – epithelial herpetic keratiits

Active against - Herpes, Pox viruses

48
Q

Why is Idoxuridine toxic?

A

It lacks specificity – also hits the host DNA polymerase

49
Q

Important druf related to Idoxuridine?

A

Trifluridine – a fluorinated Idoxuridine

50
Q

use of Trifluridine?

A

Topical herpes keratitis treatment

Primary keratoconjunctavitis

51
Q

What are cytarabine and vidarabine?

A

Nucleoside analogs of cytosine and adenine

Activated by Phosphorylation

52
Q

List of main drugs acting against DNA/RNA polymerase activity

A 
Idoxuridine
Cytarabine and vidarabine
ribavirin
acyclovir
gancyclovir
Azidothymidine
53
Q

What is Ribavirin?

A

A triazole purine nucleoside that inhibits repication of RNA/DNA viruses in vitro
Notably acts as a guanosine analog and inhibits 5’ cap on mRNA

54
Q

Ribavirin is used to treat?

A

*RSV
*Parainfuenza
Lassa Fever+Other Hemorrhagic fevers
Hep C

55
Q

Problem with ribavirin

A

Toxicity is high
Dose dependent hemolytic anemia
Mutagenic+Teratogenic

56
Q

What does Acyclovir do?

A

Easily activated by herpes thymidine kinase
Acyc. –> Acyclovir monophosphate
Acyclovir is a purine analog that competes with dGTP
Incorporation, DNA synth. blocking by blocking DNA polymerase
Triphosphate also acts as a chain terminator

57
Q

Side effects of Acyclovir

A

Nausea and Diarrhea

Tissue Irritation

58
Q

Use acyclovir for…

A

Herpes, Varicella,

EBV, CMV

59
Q

How is gancyclovir different from acyclovir?

A

Phosphation can occur from cellular enzymes

Higher risk of toxicity

60
Q

gancyclovir mode of administration.

A

Orally, IV, or intraocular

61
Q

Who do you use gancyclovir on?

A

Life or sight threatening CMV in immunocompromised hosts

62
Q

Azidothymidine/Zidovudine mechanism of action

A

Chain terminator

P’d by cell kinase

63
Q

Reverse transcriptase is (more or less) sensitive to Azidothymidine/Zidovudine than DNA-dependent?

A

More

64
Q

How is Azidothymidine/Zidovudine administered?

A

per os

Wide distribution in body

65
Q

Drugs that can enhance Azidothymidine/Zidovudine activity?

A

Acyclovir

Interferon

66
Q

Side effects of Azidothymidine/Zidovudine?

A

Granulocytopenia and Anemia

GI probs, Paresthesia, rash, liver probs, myopathy

67
Q

Increased risk of side effects if Azidothymidine/Zidovudine is taken with what drugs?

A

Ones that interact with the glucuronyl transferase pathway (aspirin, Tylenol)

68
Q

Azidothymidine/Zidovudine s typically used in treatment of…

A

HIV (w/ lamivudine)

69
Q

Lamivudine is very efficient against…

If resistance to Lam., use….

A

Hep B

Adefovir, an analog of adenosine monophosphate

70
Q

List three important nucleoside reverse tanscriptase inhibitors

A

Zidovudine, Lamivudine, Tenofovir

71
Q

The only nucleotide reverse transcriptase inhibitors

A

Tenofovir, Sofosbuvir

Pharmacology -- Test #2 (13 decks)

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